Fabrication and fit accuracy of definitive resin fixed partial dentures additively manufactured using different vat polymerization technologies

To investigate the fabrication and fit accuracy of three-unit definitive resin fixed partial dentures (FPDs) manufactured with different vat polymerization technologies, and to compare them with those manufactured subtractively. A total of 48 three-unit posterior fixed partial dentures (FPDs) were fabricated either additively from a resin intended for definitive use (VarseoSmile Triniq) with low force display (Form 4B, AM-LFD), digital light processing (Max UV, AM-DLP), and liquid crystal display (SOL, AM-LCD) technologies, or subtractively from high-impact polymer composite (breCAM.HIPC, SM) (n = 12). After digitally assessing the external, internal, and marginal surface deviations and average gaps (fit), one-way analysis of variance (ANOVA) and Tukey tests were used for the statistical analyses. Precision was defined as the average of measured values from the mean value, and was analyzed with one-way ANOVA (α = 0.05). SM and AM-LCD specimens had the highest external deviations, whereas AM-LFD specimens had the lowest (P < 0.001). AM-LCD specimens had the highest and SM specimens had the lowest intaglio deviations (P < 0.001). SM specimens had the highest marginal deviations (P ≤ 0.001). Gap values decreased in the order of AM-LCD, AM-LFD, AM-DLP, and SM (P < 0.001). Tested specimens' precision was similar (P ≥ 0.079). AM-LFD mostly led to lower trueness than the other printers and SM FPDs had the lowest marginal trueness. Tested FPDs had higher gaps than the cement space; however, SM FPDs had clinically acceptable fit, while additively manufactured FPDs exceeded clinical gap thresholds regardless of the printer. Posterior three-unit definitive fixed partial dentures fabricated with the tested resin and printers may be alternatives to those subtractively manufactured from high-impact polymer composite, given the small surface deviation differences. However, potential fit issues should be considered when a 100 µm cement space is used.